1. Field of the Invention
This invention relates to a joint assembly for a steering system of a car or the like.
2. Disclosure of the Related Art
There are various types of car steering system. For example, the rack-pinion type of car steering system has a structure described below. As shown in FIG. 8, a wheel support member 164 which supports a wheel 171 is connected with a rack bar (not shown) of a rack assembly 152 via a joint assembly 101 having a first ball joint 111. The rack teeth on the rack bar engage with a steering gear (not shown) arranged at the end portion of a steering shaft 154 extending from the steering wheel 155. According to this structure, rotational movement produced by rotating the steering wheel 155 is converted into linear movement in the car-width direction by the steering gear and the rack teeth, so that the wheel support member 164 is pulled or pushed to change the direction of the wheel 171.
AS shown in FIG. 9, a joint assembly 101, which joins the wheel support member 164 to the bar of the rack in the above structure, consists of a first ball joint 111 and a second ball joint 121. The first ball joint 111 has a housing 118 which is provided with a cylindrical threaded hole 119 at the end portion near the second ball joint. The second ball joint 121 has a ball stud 122 which is provided with a threaded stem 123. A male screw 123a of the threaded stem 123 and a female screw 118d of the cylindrical threaded hole 119 are engaged with each other, and are locked with a nut 141.
Vibration generated at the wheel 171 is transmitted to the joint assembly 101 via the wheel support member 164 when the wheel 171 rides over protrusions on the road while the car is moving or when the car suddenly starts or stops. The vibration can moreover be transmitted to the steering wheel 155 which the driver directly manipulates. Therefore, the vibration gives uncomfortableness to the driver or causes the driver to err in driving the car.